A Cytohistologic Correlation of Mucoepidermoid Carcinoma : Emphasizing the Rare Oncocytic Variant

Abstract EN

It is well-known that the morphological variability of mucoepidermoid carcinoma (MEC) of the salivary glands may lead to interpretative difficulties on fine-needle aspiration (FNA) diagnosis.

In this study we identify morphologic features that may be useful in the FNA diagnosis of MEC.

The cohort included 23 cases of MEC; cytology and histology slides were reviewed and assessed for % cystic component, extracellular mucin, mucous and intermediate cells, oncocytes, cells with foamy/clear cytoplasm, keratinized cells and lymphocytes.

On FNA 12/23 (52%) cases were diagnosed as consistent with or suggestive of MEC; 6/23 (26%) as salivary gland neoplasm and 5/23 (22%) as no tumor seen.

The cystic component was ≥50% in 18/23 (78%) and <50% in 5 cases.

The features prevalent in FNA and histology were: mucous cells (96% and 91%), extracellular mucin (91% both), intermediate cells (100 and 83%), lymphocytes (96 and 78%) and cells with foamy/clear cytoplasm (74% both).

Oncocytes were seen in 43 and 22% and keratinized cells in 48 and 13% cases.

Cases with oncocytes and lymphocytes were interpreted as favor Warthin's tumor on FNA.

Presence of mucous cells, cells with foamy/clear cytoplasm, intermediate cells and lymphocytes in a mucinous background are diagnostic indicators of MEC; presence of oncocytes should not refrain from diagnosing MEC in FNA specimens.